Primary orbital neuroblastoma.

A 35-year-old man had a primary neuroblastoma of the left orbit. Histopathologically, the tumor was composed of uniform small round cells containing argyrophilic granules arranged in nests and cords with pseudorosettes, Homer-Wright rosettes, and a fine fibrillary background matrix. Immunohistochemical staining for chromogranin was positive. Electron microscopy showed small (108- to 173-nm) dense core granules. Eight years after surgery and radiation therapy the patient was free of local recurrence and metastases. To our knowledge, primary orbital neuroblastoma has been reported only once previously. Neuroblastoma, which occurs most frequently in children and has an incidence in the United States of 500 cases annually, is a distinctly unusual tumor in adults.